Filling mixture for shoe bottoms



Nov. 7, 1944;

RQA. HOLBROOK ETA; 2,362,378 FILLING IIHURE FOR 530E BUTTONS Filed lay 23', 1940 INVENTORS Patented Nov. 7, 1944 OFFICE FILLING MIXTURE FoR s-HoE Bo'rToMs' Ralph 'A, Holbrook,'Beacon Falls, and Willis 0.

Hooker, Shelton,

Conn,

assignors to The Sponge Rubber Products, Company, Shelton,

,Conn., a corporation of Connecticut Application. May 23, 1940, Serial N6. 336,162

, '5 Claims. (01. 260-755) This invention relates to mixtures of substances forming a spreadable mass of material particularly suited for-filling the cavity between innersole and outersole of a'shoe during fabrication orrepair. The invention further relates to preferred methods for making the mixture and applying it to the shoe bottom.

Characteristics desirable in mixtures for this purpose include; ability to be smeared thinly over the inverted innersole in the manner of a plastic; ability to "flow sufiicientl-yunder heat and pressure to become molded into full conformity with the boundaries of the cavity; ability to set quickly and without shrinking; or cracking; ability to form, when set, a'tough, flexible and somewhat resilient layer separating the innersole from the outersole and which shall be proof against creeping and bunchingwhenthe shoe is being, Worn;

and freedom from ingredients which can injure either the leather or other materials of the shoe,- or the foot of the wearer. It isalso desirable that a shoe bottom filling material shall .be nonabsorbent and waterproof, also that it be able to breathe as does the porous leather soles between which it is sandwiched in the shoe bottom. It is further desirable that the mixture shall be inexpensive, which end can best be attained by the use of by-products or reclaimed materials as ingredients. I

Former attempts to produce a shoe bottom filling material having the characteristics enumer v ated have met with serious obstacles. These obstacles have resulted in poor spreading and molding quality, or slow unsatisfactory setting performance of theatteinpted mixtures, or lack of V uniformly distributed coherence, adherence and porosity of the fillingin the shoe bottom with resultant creeping and bunching of the filling material when the shoe is in use. f i Formerlyproposed use of liquid rubber dispersion as aflowabl'e binder mixedwith filler bodies comprising ground cork or equally solid particles of other substances has required tim'e wasting waits until the liquidin the rubber dis persion evaporates and permits fsetting of the mixture afterits application to the shoe. Also the formerly proposed use of small particles hav ing a solid body character comprising the filler ingredient of f the mixture has necessitated the addition of special agents" among the ingredients of themixture to effect, an fopeningj' or porosity thereof in order thatair may be admitted to the interior of the mass and aid in the evaporation of. its liquid content, This; fopenfycharacter'of the mixture is furtherneededjto help maintain,

uniform distribution of the binder throughout the mass after themixture has been smeared, spread or wiped'intoits filling position. in the shoe bottom, and to prevent balling or rolling up ,of the material in' the "course of spreading it into a thin-cavity filling layer.

The present discovery teaches that a satisfactory self-openingquality. may be imparted to a spreadable mixture of the character-concerned. by the use of filler bodies or particles'composed of ragged membranousscrapsor fragments-of tough, flexible and preferably resilient substances having the distinctive physical property ofpossessing a minutely intersticed, creviced or pouchedstructurew While ground-up particles of natural sponge or artificial cellulose sponge might serve, some of thenpurposes of the ragged membranous, scraps referred to, particularly good success has resulted from the use as filler bodies of tiny particles of vulcanized rubber intersticedor minutely. creviced or pouched because. made up of an attenuated network of thin, tough, elastic, conjoined, curved, membranous walls preferably having their free edges lacineated and shaped to Pr sent minute retentive or hook-like protuberancesl In particles'ofsuch structural nature the projecting of affr'agmentary portion of one wall away from the surface of aconjoined wall in itself forms a retentive protuberance even where the wall edges themselves are smooth.

Curling of the free marginal edge portions of the walls also forms retentive elements. If the membranous walls of such a particle are perfo-, rate, this alsowill add to the mass opening effectiveness ofthe improved type of filler 'body. Th present discovery furtherteaches that filler bodies having thephyslcal properties mentioned may be produced, by disrupting, distorting, and irregularly tearing apart vulcanized cellular rubber With filler bodies of the kinda'bove indicated,

various'bihdersmay be used. Particular success has attended the mixing with such filler bodies of granules of a" 'wax'y'veget'able substance softened and made adherent by wetting the granules with a mineral oil. Specifically the waxy substance may be aresin, or rosin, while the oil may be para'flin oil. Variations from these indicated ingredients are mentioned hereinafter. Further particulars as to the qualities and reactions of such a mixture and as to the ways of compounding it and applying it as a filling to a shoe bottom cavity are also hereinafter given with particular reference to the accompanying sheet of drawings wherein:

Fig. 1 shows an inverted partially assembled shoe with a filling material embodying these im-' provements being applied to the bottom thereof.

Fig. 2 shows a microscopically enlarged fragmentary view of a single particle of the improved filler body.

Figs. 3 to 8, inclusive, are fragmentary views drawn on a still further enlarged scale taken in section respectively on the planes 33, 44, 5-5, 6B, l'--I, and 88, in Fig. 2, looking in the direction of the arrows.

Figs. 9 and 10 'are correspondingly enlarged fragmentary views taken in section respectively on the planes 9-9 and Ill-l in Fig. 3.

. Fig. 11 is an enlargedfragme'ntary view taken in section on the plane H-H in Fig. 2 looking in the direction of the arrows and indicates the corresponding interlocking parts of a neighbor-.

ing filler particle.

Fig. 12 shows on the same scale as does Fig. 2 a fragmentary portion of a single filler particle carrying retained thereagainst granules of a binder substance} The physical characteristics of the improved filler particle structure are evident from the microscopically enlargedviews thereof shown in Figs. 2 to 10 inclusive. In the case of particles of ground up or shredded vulcanized cellular rubber stock whose membranous walls have been torn apart in the grinding process, the tearing action leaves certain of the flexible and elastic membranous walls 9 with serrated or rough edges of hook-like shape forming retentive protuberances ID. The curved nature of the marginal portions of the walls also gives rise to further protuberances i I some of which may also be of hook-like nature. Also resulting from the irregular tearing'apart of the curved membranous walls encompassing the interior cells of the original vulcanized sponge rubber stock are apertures [2 which may be bordered by wall edges shaped to form retentive protuberance I3. It will be ob served that the projection of a fragmentary portion M of one wall away fromthe surface l of a conjoined wall also forms in effect a retentive protuberance. 7

While operations of a nature which tear apart the sponge rubber, commonly referred to in the art as grinding, have been found effectively to produce particles having these characteristics, some such characteristics will, result from operations of a nature which cut the sponge rubber into small particles. In either of these methods of dividing the original sponge rubber into particles having the novel characteristics described, it has been found to be of advantage that the resulting particles shall vary in size, in order that a certain proportion of the finest particles or crumbs shall be small enough to enter and occupy voids which would be leftzby the larger particles alone and thus prevent uneven distribution of such voids.

The various; forms of-retentive protuberances perform several functions of importance to the desirable performance of the improved filling mixture. First they'effect a yieldable mechanical interlocking with crevices and/ or pouches formed by similar protuberances, as H in Fig. 11, on

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neighboring like filler particles. They add to the plastic nature of the physical mixture by virtue of their relative weakness and ability to yield and distort in a manner to fit into available spaces when the mixture is compacted or squeezed together in the act of smearing it against the shoe bottom. Because of their resilient nature, these tiny protuberances further tend to spring back somewhat after being pressed or matted together or otherwise distorted and thus automatically promote an opening action throughout the mass of filling mixture which gives better access for air to enter and aid in the rapid and uniform setting 'of the binder; They furnish mechanical holding means for relatively much smaller solid granules l6 of a resinous binder substance or rosin.

The mechanical interlocking of the retentive protuberances on neighboring contacting tiny filler particles and the retention of the still smaller grains or granules l6 of oil-softened rosin or other binder material well distributed over the irregular surfaces of the filler particles as shown in Fig. 12, is aidedby the presence of irregular apertures l2 in the membranous Walls. Some of the protuberances Ill 0r ll and some of the granules Hi of the binder substance are certain to enter and become separably lodged in these apertures. Thus a plurality of the binder solids are lodged shiftably against and separably retained by the disrupted creviced and pouched cellular walls of a single filler fragment in scattered and spaced relation.

' With this understanding of the valuable properties of the distinctive intersticed creviced and pouched structural make-upof each tiny filler particle, whose over-all dimension may be 1 5' inch or less and still contain all of the minute intersticed and lacineated detail illustrated in Fig. 2, it will be appreciated that a radically different performance and reactance may be expected of a mixture containing filler body particles of this nature than is the performance and reactance of a mixture in which only solid particles of ground rubber, ground cork, or other equally solid substances are used.

In preferred practice, and subject to variations as desired, pounds of vulcanized sponge rubber scrap in the formof dry particles, sifted to' eliminate particles which will not pass through a 3%" screen, are dumped into a mixer, together with 100 pounds of pulverized rosin and 5%; quarts of a thin paraffin oil. The whole istumbled' or otherwise thorougly mixed together causing the rosin to be thoroughly wetted by the oil and causing the oil to coat all surfaces of the rubber filler particles. The intersticed creviced and pouched nature of the filler particles presents in a given cubical dimension of space much more surface area receptive to coating by the oil, and receptive toa distribution thereover of the granules of rosin, than would be possible to solid filler particles of any substance. This therefore makes for more intimate, uniform and thorough distribution of the oil softened rosin granules in relation to the filler bodies and produces more ready response of the whole binder content to the application of heat when the mixture I1 is troweled into the shoe bottom cavity by means of the heated metallic blade of a hand tool l8, or by a hot presser roller or other heated pressing.

means. With or without heating, the oil promotes adherence of the binder granules to the walls of the sponge rubber filler fragments. Sufficient resinous binder is used to bond the sponge rubber particles at their points of contact preferably without filling up or badly clog-.

ging the desirable interstices throughout the mixtune thereby to preserve the open and workable consistency of the mass. Sufficient oil is used to coat the sponge rubber particles and wet the resinous binder.

In place of smearing a bulk mass of our improved filler mixture against the bottom surface of the inner sole of the inverted shoe, a preshaped sole-like blank may be cut or stamped out of a sheet of stock of suitable thickness composed of our improved mixture of materials, such blank fitting nicely the cavity in the shoe bottom which is to be filled. Such stock may be prepared for sale in suitable fiat or rolled sheetform by warming a mass of the mixture which has hereinbefore' pressure and heat but no troweling or like hand tool operation to apply to the shoe.

Limited departure from the substances which have herein been proposed for binder may be resorted to without losing all of the advantages which arise from the nature of the filler particles concerned. Waxy binders to serve the purpose of granules of rosin may be selected from a group of mineral substances and softening or lubricative oils may be chosen from a ground vegetable liquids. Castor oil may serve a softening or lu bricative purpose. Both the sticky or solidifiable substance and the softening or lubricative substance may be such as will assume a liquid form at ordinary room temperatures. Shellac used as a liquid substitute for solid rosin will be found to have valuable properties. Where both binder substances are liquid 'no preheatin to make the mixture spreadable or workable will be required.

With the foregoing specifications as guide to aid in-availing of the present improvements in shoe filler mixtures, it will be understood that many of the advantages thereof may be obtained It will be understood that there are many uses" for our improved composition other than that of filling shoe bottoms. Among these there may be mentioned the calking of seams and crevices in marine and building structures to make weatherproof and the filling of various cavities in assembled articles whose use involves the flexing or stretching of the walls thereof.

We claim:

1. A shoe filler comprising particles of shredded sponge rubber mixed with sufficient. resinous binder yieldably to-bond the sponge rubber particles at only their points of contact, and an oil in quantity sufiicient to coat the sponge rubber particles and wet the resinous binder.

2. A shoe bottom filler mixture including, flexible elastic filler fragments composed of disrupted membranous walls of cellular vulcanized rubber, minute binder solids comprising granules of resinous binder so tiny that a plurality of said granules are shiftably lodged against and separably retained by said disrupted cellular walls of a single filler fragment in scattered relation over the surface of said walls, and a sufiicient quantity of an oil to coat the exposed surfaces of said rubber filler fragments and to wet said granules of resinous binder for causing the latter to soften and become more sticky thereby to promote adherence of said granules to said rubber Walls in their said scattered relation.

3. A shoe bottom filler mixture including, raggedly contoured flexible elastic filler fragments composed of conjoined disrupted membranous walls. of cellular vulcanized rubber, minute Sticky filler fragments and to wet said granules of resin for causing the latter to soften and become more sticky thereby to promote adherence of said granules to said rubber walls in their said scattered relation.

4. A shoe bottom filler mixture including, raggedly contoured flexible elastic filler fragments sufficiently small to pass through screening apertures of the order of three thirty-seconds of an inch in breadth composed of conjoined disrupted membranous walls of cellular vulcanized rubber, minute sticky binder solids comprising granules of resin so tiny that a plurality of said granules are shiftably'lodged against and separably retained by the contours of said disrupted cellular walls of a single filler fragment in scattered relation over the surface of said walls, and a suflicient quantity of an oil to coat all exposed surfaces of said rubber filler fragments and to wet said .granules of resin for causing the latter to soften and become more sticky thereby to promote adherence of said granules to said rubber walls in their said scattered relation.

5. A shoe bottom filler mixture including in an exemplary batch approximately one hundred pounds of free minutely intersticed filler parti cles composed of finely fragmented cellular rubber stock, approximately one hundred pounds of pulverized rosin, and approximately five and one half quarts of thin paraffin oil.

RALPH A. HOLBROOK. WILLIS O. HOOKER. 

